Cooling device for cooling a heat-generating component, and electronic apparatus having the cooling device

ABSTRACT

A cooling device having a heat receiving portion, a heat radiating portion, a heat pipe, and a fan. The heat receiving portion is held on a wiring board and thermally connected to a heat-generating component. The heat radiating portion radiates the heat generated by the heat-generating component, at a position remote from the heat receiving portion. The heat pipe transfers the heat generated by the heat-generating component, from the heat receiving portion to the heat radiating portion. The heat pipe couples the heat receiving portion and the heat radiating portion. The fan applies cooling air to the heat radiating portion. The fan is coupled to the heat radiating portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromprior Japanese Patent Application No. 2004-289012, filed Sep. 30, 2004,the entire contents of which are incorporated herein by reference.

BACKGROUND

1. Field

The present invention relates to a cooling device having aheat-radiating portion for radiating heat from a heat-generatingcomponent and a fan for applying cooling air to the heat radiatingportion, and to an electronic apparatus, such as a portable computer,which incorporates this cooling device.

2. Description of the Related Art

A CPU is incorporated in electronic apparatuses such as portablecomputers. The heat that a CPU generates while operating increases asits data-processing speed rises or as it performs more and morefunctions. The higher the temperature of the CPU, the less efficientlythe CPU operates or the more likely it may fail to operate.

Any electronic apparatus comprising a CPU that generates much heat whileoperating incorporates a cooling device that cools the CPU. The coolingdevice is provided in the housing of the electronic apparatus, alongwith the other major components of the apparatus, such as the wiringboard and the hard disk drive.

The conventional cooling device has a heat receiving portion, a heatradiating portion, a heat pipe, and a fan. The heat receiving portion isthermally coupled to a CPU. The heat radiating portion radiates isspaced apart from the heat receiving portion and radiates heat from theCPU. The heat pipe transfers the heat of the CPU to the heat radiatingportion. The fan has an air outlet port, through which cooling air issupplied to the heat radiating portion.

In the conventional cooling device, the heat of the CPU is transferredfrom the heat receiving portion through the heat pipe to the heatradiating portion. The heat radiating portion is cooled with the coolingair applied from the fan. The heat of the CPU, transferred to the heatradiating portion, is released from the housing by virtue of heatexchange with the cooling air. The ambient temperature of the CPU isthereby maintained at such a value that the CPU operates well.

The heat pipe mechanically connects the heat receiving portion and theheat radiating portion. Thus, the heat receiving portion, heat radiatingportion and heat pipe constitute one module. The module is held on thewiring board, on which the heat receiving portion is provided, with theCPU mounted on it. The fan is fastened, with screws, to the innersurface of the housing, with its air outlet port opposed to the heatradiating portion. The fan and heat radiating portion are located sideby side, away from the heat receiving portion.

In the conventional cooling device, the position of the heat radiatingportion is determined by that of the heat receiving portion that is heldon the wiring board. By contrast, the position of the fan is determinedby that of the inner surface of the housing. In other words, theirpositions depend on the positions of different components, which arelikely to change. Their positions inevitably differ from the desiredones. In some cases, a large gap develops between the heat radiatingportion and the fan, and the cooling air flowing toward the heatradiating portion inevitably leaks through this gap.

A cooling device is known, which has a duct that extends to the airoutlet port of a fan to prevent the leakage of cooling air. In thiscooling device, the duct surrounds the heat radiating portion, therebypreventing the cooling air from leaking through the gap between the heatradiating portion and the air outlet port of the fan. Jpn. Pat. Appln.KOKAI Publication 2003-101272, for example, discloses an electronicapparatus that has a cooling device of this type.

In the cooling device disclosed in the above-identified Japanesepublication, the heat pipe connects the heat receiving portion to theheat radiating portion that is surrounded by the duct. The duct hasthrough holes that guide the heat pipe. These holes have a far largerdiameter than the heat pipe, in order to compensate for the changes inposition of the fan and heat radiating portion. Inevitably, a gapdevelops between the heat pipe and the rim of each through hole.

Consequently, the cooling air coming from the fan leaks through the gap.The cooling air is applied to the heat radiating portion in a smalleramount than otherwise. The heat radiating portion cannot be efficientlycooled. Ultimately, the CPU may not be cooled sufficiently.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the invention, andtogether with the general description given above and the detaileddescription of the embodiments given below, serve to explain theprinciples of the invention.

FIG. 1 is a perspective view of a portable computer according to a firstembodiment of this invention;

FIG. 2 is a perspective view of the portable computer, showing thecooling device incorporated in the housing of the portable computer andconfigured to cool the CPU of the portable computer;

FIG. 3 is a perspective view, representing the positional relation thatthe cooling device and the CPU assume in the first embodiment of theinvention;

FIG. 4 is a perspective view illustrating the positional relation thatthe heat receiving portion, heat radiating portion and heat pipe take inthe first embodiment of the invention;

FIG. 5 is a sectional view depicting the CPU and heat receiving portionthat are thermally connected in the first embodiment of the invention;

FIG. 6 is a sectional view, illustrating the heat pipe and the fin unitthat are thermally connected in the first embodiment of the invention;

FIG. 7 is a plan view of the cooling device used in the first embodimentof the invention;

FIG. 8 is a plan view showing the fin unit and centrifugal fan that arespaced apart in the first embodiment of the invention;

FIG. 9 is a plan view of a cooling device according to a secondembodiment of this invention;

FIG. 10 is a plan view of a cooling device according to a thirdembodiment of the present invention;

FIG. 11 is a plan view showing the fin unit and centrifugal fan that arespaced apart in the third embodiment of the invention;

FIG. 12A is a side view showing the heat pipe having its heat-radiatingend fitted in the slit of the second bracket in the third embodiment;

FIG. 12B is a side view showing the heat pipe having its heat-radiatingend removed from the slit of the second bracket in the third embodiment;

FIG. 13 is a plan view of a cooling device according to a fourthembodiment of the present invention;

FIG. 14A is a side view showing the heat pipe having its heat-radiatingend fitted in the slit of the first bracket in the fourth embodiment;

FIG. 14B is a side view showing the heat pipe having its heat-radiatingend removed from the slit of the first bracket in the fourth embodiment;

FIG. 15A is a side view showing the heat pipe having its heat-radiatingend fitted in the slit of the second bracket in the fourth embodiment;

FIG. 15B is a side view showing the heat pipe having its heat-radiatingend removed from the slit of the second bracket in the fourthembodiment;

FIG. 16 is a plan view of a cooling device according to a fifthembodiment of the invention; and

FIG. 17 is a plan view of the cooling device according to the fifthembodiment, showing the fin unit, centrifugal fan and support plate thatare separated from one another.

DETAILED DESCRIPTION OF SEVERAL EMBODIMENTS

The first embodiment of the invention will be described, with referenceto FIGS. 1 to 8.

FIGS. 1 and 2 show a portable computer 1, i.e., an electronic apparatusaccording to this invention. The portable computer 1 comprises a mainunit 2 and a display unit 3. The main unit 2 has a housing 4 shaped likea flat box. The housing 4 has a bottom wall 4 a, left and right sidewalls 4 b, front wall 4 c and top wall 4 d. The top wall 4 d supports akeyboard 5.

The display unit 3 has a display housing 6 and a liquid-crystal displaypanel 7. The display housing 6 holds the liquid-crystal display panel 7.The display housing 6 is coupled to the rear edge of the housing 4 withhinges (not shown) and can be rotated between a closed position and anopened position. The liquid-crystal display panel 7 has a display screen7 a, which is exposed outside through the opening 8 made in the front ofthe display housing 6.

As FIG. 2 shows, the housing 4 contains a printed wiring board 10. Theprinted wiring board 10 is secured to the bottom wall 4 a and extendsparallel thereto. A central processing unit 11 (hereinafter referred toas “CPU”) is mounted on the upper surface of the printed wiring board10. The CPU 11 is an example of a heat-generating component. As can beseen from FIGS. 3 and 5, the CPU 11 is a BGA-type semiconductor package.The CPU 11 has a base substrate 12 and an IC chip 13. The base substrate12 is soldered to the upper surface of the printed wiring board 10. TheIC chip 13 is mounted on the center part of the base substrate 12. TheIC chip 13 generates much heat while operating. The IC chip 13 must becooled to keep performing stable operation.

As shown in FIG. 2, the housing 4 contains a cooling device 15 that isconfigured to cool the CPU 11. As FIGS. 2 to 4 show, the cooling device15 comprises a heat receiving portion 16, a fin unit 17, a heat pipe 18,and a centrifugal fan 19.

The heat receiving portion 16 is provided on the CPU 11. It isrectangular, a little larger than the IC chip 13. The heat receivingportion 16 has a heat-receiving block 20 a and a top plate 20 b. Theblock 20 a and plate 20 b are made of metal having high thermalconductivity, such as copper or aluminum alloy.

The lower surface of the heat-receiving block 20 a is flat, serving as aheat-receiving surface 21. The heat-receiving surface 21 faces the ICchip 13 of the CPU 11. The heat-receiving block 20 a has a groove 22 cutin the upper surface. The groove 22 runs across the block 20 a and opensat the circumferential surface thereof. The top plate 20 b is secured tothe upper surface of the heat-receiving block 20 a by means of, forexample, caulking. The top plate 20 b covers the groove 22 from above.

As FIGS. 3 and 5 depict, a spring member 23 holds the heat receivingportion 16 to the printed wiring board 10. The spring member 23 has asquare pushing plate 24 and four arms 25. The pushing plate 24 has aprojection 26 at the center part of the upper surface of the top plate20 b. The arms 25 extend in radial direction from the four corners ofthe pushing plate 24. Four bosses 27 protrude from the upper surface ofthe printed wiring board 10. Four screws 28 are driven in these bosses27, respectively, fastening the distal ends of the arms 25 to the bosses27.

The arms 25 resiliently press the pushing plate 24 on the top plate 20b. The heat-receiving surface 21 of the heat-receiving block 20 a istherefore pushed to the IC chip 13. Thermally conductive grease 29 isapplied between the IC chip 13 and the heat-receiving surface 21. As aresult, the heat receiving portion 16 takes a specific position withrespect to the printed wiring board 10 and the heat-receiving surface 21is thermally connected to the IC chip 13.

The fin unit 17 is a heat radiating portion. As FIG. 6 shows, the finunit 17 has a plurality of heat-exchanging plates 31. Theheat-exchanging plates 31 are made of metal having high thermalconductivity, such as copper. Each heat-exchanging plate 13 has twoflanges 31 a and 31 b. The flanges 31 a and 31 b have been formed bybending the upper and lower edges of a rectangular plate, each at rightangle. Each heat-exchanging plate 31 has its flanges 31 a and 31 babutting on those of the next heat-exchanging plate. Thus, theheat-exchanging plates 31 are arranged parallel to, and spaced apartfrom, one another.

The fin unit 17 has a first end part 17 a and a second end part 17 b.The first end part 17 a is located at one end of the row of theheat-exchanging plates 31. The second end part 17 b is located at theother end of the row of the heat-exchanging plates 31.

The fin unit 17 extends along the left side wall 4 b of the housing 4and is spaced apart from the heat receiving portion 16 that is providedon the printed wiring board 10. The fin unit 17 is opposed to an exhaustport 32 that is made in the left side wall 4 b.

The heat pipe 18 is a heat-transferring component. As FIG. 4 shows, theheat pipe 18 has a container 34 containing liquid coolant. The container34 has a heat-receiving part 35 a, a heat-radiating part 35 b, and acurved part 35 c. The heat-receiving part 35 a is a flat member that isfitted in the groove 22 cut in the heat-receiving block 20 a. Theheat-receiving part 35 a is clamped between the top plate 20 b and theinner surface of the groove 22. Thus, the heat-receiving part 35 a ofthe heat pipe 18 is thermally connected to the heat receiving portion16.

The heat-radiating part 35 b penetrates the center part of eachheat-exchanging plates 31 of the fin unit 17 and is thermally connectedto the heat-exchanging plates 31. The distal end of the heat-radiatingpart 35 b protrudes from the fin unit 17, more precisely from the secondend part 17 b of the fin unit 17.

The curved part 35 c extends between the heat-receiving part 35 a andheat-radiating part 35 b and connects these parts 35 a and 36 b to eachother. Connected by the curved part 35 c, the heat-receiving part 35 aand heat-radiating part 35 b extend at right angles to each other.

The container 34 of the heat pipe 18 is a pipe made of metal such asaluminum. It is rigid, not liable to be bent. Therefore, the container34 couples the heat receiving portion 16 and the fin unit 17 and holdsthem in a predetermined positional relation. Thus, the heat receivingportion 16, fin unit 17 and heat pipe 18 constitute one module. Hence,the position of the fin unit 17 takes with respect to the housing 4 andprinted wiring board 10 is determined by the position of the heatreceiving portion 16.

As shown in FIGS. 2 and 3, the centrifugal fan 19 has a fan case 37 andan impeller 38. The fan case 37 is shaped like a flat box and has a pairof inlet ports 39 (only one is shown) and an outlet port 40. The outletport 40 is a rectangular opening and is as long as the fin unit 17.

The fan case 37 contains the impeller 38 and a motor (not shown). Theimpeller 38 is fastened to the shaft of the motor. When driven by themotor, the impeller 38 draws air into the fan case 37 through the inletports 39. In the fan case 37, the air flows to the center of theimpeller 38. Then, the air flows from the circumference of the impeller38 to the outlet port 40 of the fan case 37.

The centrifugal fan 19 is integrally formed with the fin unit 17, withits outlet port 40 opposed to the fin unit 17. The fin unit 17 has afirst bracket 41 and a second bracket 42 as illustrated in FIGS. 4 to 8.The brackets 41 and 42 hold the fan case 37.

The first bracket 41 is fastened to the heat-exchanging plate 31 that islocated at the first end part 17 a of the fin unit 17. The first bracket41 projects from the first end part 17 a toward the fan case 37. Thefirst bracket 41 is shaped like a strip and as long as the fan case 37is deep. The fan case 37 contacts, at one side, the first bracket 14.

The first bracket 41 has a first holding part 43 and a second holdingpart 44. The first holding part 43 has been formed by bending the distalend of the first bracket 41 upward at right angle. The first holdingpart 43 faces the first end part 17 a of the fin unit 17 and contactsthat side of the fan case 37 which faces away from the outlet port 40.

The second holding part 44 lies between the first end part 17 a of thefin unit 17 and the first holding part 43. The second holding part 44has a standing strip 45 a and a holding strip 45 b. The standing strip45 a vertically extends from the side edge of the first bracket 41. Theholding strip 45 b horizontally extends from the upper edge of thestanding strip 45 a and opposes the first bracket 41. The holding strip45 b cooperates with the first bracket 41, resiliently clamping oneside-part of the fan case 37.

The second bracket 42 is integrally formed with the heat-exchangingplate 31 that is located at the second end part 17 b of the fin unit 17.The second bracket 42 extends from the second end part 17 b of the finunit 17 toward the fan case 37. The other end part of the fan case 37 ismounted on the second bracket 42. The second bracket 42 has a screw hole46. The screw hole 46 is axially aligned with a through hole 47 that ismade in the other-side part of the fan case 17.

To fasten the centrifugal fan 19 to the fin unit 17, the fan case 37 ismounted on the first bracket 41 and second bracket 42. Then, the end ofthe fan case 37, which faces away from the outlet port 40, abuts on thefirst holding part 43 of the first bracket 41. At the same time, theone-side part of the fan case 37 slips into the gap between the firstbracket 41 and the holding strip 45 b of the second holding part 44 andis clamped between the first bracket 41 and the holding strip 45 b.Further, the through hole 47 of the fan case 37 comes into axialalignment with the screw hole 46 of the second bracket 42.

A screw 48 is inserted from above into the through hole 47 of the fancase 37 and then driven into the screw hole 46 of the second bracket 42.As a result, the screw 48 fastens the fan case 37 to the first bracket41 and second bracket 42. The fin unit 17 and the centrifugal fan 19 arethereby coupled.

Once the centrifugal fan 19 has been fastened to the fin unit 17, theoutlet port 40 of the fan case 37 faces the fin unit 17, providing nogaps between the fin unit 17 and the outlet port 40.

When the portable computer 1 is used, the IC chip 13 of the CPU 11generates heat. The heat receiving portion 16 transmits the heat fromthe IC chip 13 to the heat-receiving part 35 a of the heat pipe 18. Theliquid coolant in the heat-receiving part 35 a is heated and evaporated.The resultant vapor flows from the heat-receiving part 35 a to theheat-radiating part 35 b. The vapor is condensed in the heat-radiatingpart 35 b. The condensation releases the heat from the heat-radiatingpart 35 b. The heat is conducted to the fin unit 17 and radiated fromthe heat-exchanging plates 31.

The vapor is liquefied into liquid coolant in the heat-radiating part 35b. The liquid coolant flows back into the heat-receiving part 35 a, byvirtue of capillary force. In the heat-receiving part 35 a, the liquidreceives the heat from the IC chip 13. As the liquid coolant repeatedlyundergoes evaporation and condensation, the heat generated by the ICchip 13 is transferred to the fin unit 17.

The motor provided in the fan case 37 starts driving the impeller 38when the temperature of the IC chip 13 reaches a predetermined value.Thus driven, the impeller 38 draws air from the housing 4 into the fancase 37 through the inlet ports 39. The air thus drawn is applied ascooling air from the outlet port 40. The cooling air flows through thegaps between the heat-exchanging plates 31 of the fin unit 17.

As the cooling air so flows, it takes the heat from the heat-exchangingplates 31, i.e., the heat generated by the IC chip 13 and transmitted tothe plates 31. The cooling air heated due to the heat exchange at thefin unit 17 is discharged from the main unit 2 of the portable computer1 through the exhaust port 32 of the housing 4.

The first and second brackets 41 and 42 of the fin unit 17 hold thecentrifugal fan 19 that applies cooling air to the fin unit 17, in thefirst embodiment of the invention. In other words, the centrifugal fan19 is held in a specific position with respect to the fin unit 17 thatreceives the cooling air. It is well aligned with the fin unit 17 interms of position.

Therefore, there are no gaps between the fin unit 17 and the centrifugalfan 19. The cooling air would not leak at the junction between the finunit 17 and the centrifugal fan 19. The cooling air is always applied ina sufficient amount to the fin unit 17. The fin unit 17 can thereforeradiate heat at high efficiency. Thus, the cooling device 15 can attainhigh heat-radiating efficiency without fail. That is, the device 15 cancool the CPU 11 well, helping the CPU 11 to operate as is desired.

To separate the fin unit 17 and the centrifugal fan 19 from each other,it suffices to take out the screw 48 from the screw hole 46 of thesecond bracket 42 and then to pull the fan case 37 from the secondholding part 44. Thus, it is easy to remove the centrifugal fan 19 fromthe fin unit 17. This facilitates the maintenance of the centrifugal fan19.

To reduce this embodiment to practice, a seal made of heat-resistancerubber or foamed rubber may be interposed between the fin unit 17 andthe outlet port 40 of the fan case 37. Then, no cooling air will leak atthe boundary between the fin unit 17 and the fan case 37. This canfurther enhance the heat-radiating efficiency of the fin unit 17.

This invention is not limited to the first embodiment described above. Asecond embodiment of the invention will be described, with reference toFIG. 9.

The second embodiment differs from the first embodiment in that two heatpipes 50 and 51 transfer heat from the heat receiving portion 16 to thefin unit 17. In any other structural respect, the cooling device 15according to the second embodiment is identical to the first embodiment.

In the second embodiment, the heat pipes 50 and 51 extend parallel toeach other, between the heat receiving portion 16 and the fin unit 17.The heat pipe 50 has a heat-receiving part 50 a and a heat-radiatingpart 50 b. Similarly, the heat pipe 51 has a heat-receiving part 51 aand a heat-radiating part 51 b.

The heat-receiving block 20 a of the heat receiving portion 16 has twogrooves 52 a and 52 b cut in the upper surface. The grooves 52 a and 52b extend parallel and spaced apart. The heat-receiving part 50 a of theheat pipe 50 and the heat-receiving part 51 a of the heat pipe 51 arefitted in the grooves 52 a and 52 b, respectively. The heat-radiatingpart 50 b of the heat pipe 50 and the heat-radiating part 51 b of theheat pipe 51 penetrate the heat-exchanging plates 31 of the fin unit 17.Therefore, the heat-receiving part 50 a of the heat pipe 50 and theheat-receiving part 51 a of the heat pipe 51 are thermally connected tothe heat receiving portion 16, and the heat-radiating parts 50 b and 51b are thermally connected to the fin unit 17.

FIGS. 10 to 12 depicts a third embodiment of this invention.

In the third embodiment, the fin unit 17 has the first bracket 41 andthe fan case 37 has a second bracket 61. The first bracket 41 has thesame structure as its counterpart of the first embodiment. It istherefore designated at the same reference numeral and will not bedescribed in detail.

The second bracket 61 is a flat plate. The second bracket 61 is securedto one side of the fan case 37 and protrudes from the outlet port 40toward the second end part 17 b of the fin unit 17. The second bracket61 has a slit 62. In the slit 62, there is removably inserted the distalend of the heat-radiating part 35 b of the heat pipe 18. The slit 62extends straight from the distal end of the second bracket 61 toward thefan case 37. The slit 62 is narrower than the diameter of distal end ofthe heat-radiating part 35 b. The slit 62 has, at the midpoint, aholding part 63, in which the distal end of the heat-radiating part 35 bis fitted.

To assemble the centrifugal fan 19 into the fin unit 17, the distal endof the heat-radiating part 35 b of the heat pipe 18 is inserted into theslit 62 of the second bracket 61. For the same purpose, the fan case 37is mounted on the first bracket 41, with its one side projecting fromthe fin unit 17.

Next, the distal end of the heat-radiating part 35 b is guided to theholding part 63 through the slit 62, until the side of the fan case 37,which faces away from the outlet port 40, abuts on the first holdingpart 43 of the first bracket 41. Then, the one-side part of the fan case37 is fitted in the gap between the first bracket 41 and the holdingstrip 45 b of the second holding part 44.

Thus, the first and second brackets 41 and 61 couple the fan case 37 andthe fin unit 17 together.

In the third embodiment, too, the centrifugal fan 19 can assume aspecific position with respect to the fin unit 17 that receives coolingair. Hence, the centrifugal fan 19 and the fin unit 17 can be positionedwith respect to each other with high precision. No gaps are thereforemade between the centrifugal fan 19 and the fin unit 17. Thus, thecooling air would not leak at the junction between the fan 19 and thefin unit 17.

FIGS. 13 to 15 illustrates a fourth embodiment of the present invention.

The fourth embodiment differs from the first embodiment in the structurethat connects the fin unit 17 and the centrifugal fan 19. In any otherstructural respect, the cooling device 15 according to the fourthembodiment is identical to the first embodiment.

As FIG. 13 shows, the fan case 37 has two brackets 71 and 72, which areshaped like a flat plate. The first bracket 71 is secured to one side ofthe fan case 37 and protrudes from the outlet port 40 toward the firstend part 17 a of the fin unit 17. The second bracket 72 is secured tothe opposite side of the fan case 37 and protrudes from the outlet port40 toward the second end part 17 b of the fin unit 17. The first bracket71 and second bracket 72 therefore oppose each other across the outletport 40.

The first bracket 71 has a slit 73. In the slit 73, there is removablyinserted the proximal end of the heat-radiating part 35 b of the heatpipe 18. The slit 73 extends straight from the distal end of the firstbracket 71 toward the fan case 37. The slit 73 is narrower than thediameter of the proximal end of the heat-radiating part 35 b. The slit73 has, at the midpoint, a holding part 74, in which the proximal end ofthe heat-radiating part 35 b is fitted.

The second bracket 72 has a slit 75. In the slit 75, there is removablyinserted the distal end of the heat-radiating part 35 b of the heat pipe18. The slit 75 extends straight from the distal end of the secondbracket 72 toward the fan case 37. The slit 75 is narrower than thediameter of the distal end of the heat-radiating part 35 b. The slit 75has, at the midpoint, a holding part 76, in which the distal end of theheat-radiating part 35 b is fitted.

To assemble the centrifugal fan 19 into the fin unit 17, the proximalend of the heat-radiating part 35 b of the heat pipe 18 is inserted intothe slit 73 of the first bracket 71. For the same purpose, the distalend of the heat-radiating part 35 b of the heat pipe 18 is inserted intothe slit 75 of the second bracket 72. Further, the heat-radiating part35 b is pushed along the slits 73 and 75, until the proximal and distalends of the heat-radiating part 35 b are fitted in the holding part 74and 76, respectively.

Thus, the first and second brackets 71 and 72 couple the fan case 37 andthe fin unit 17 together.

In the fourth embodiment, the centrifugal fan 19 can assume a specificposition with respect to the fin unit 17 that receives cooling air.Hence, the centrifugal fan 19 and the fin unit 17 can be positioned withrespect to each other with high precision. No gaps are therefore madebetween the centrifugal fan 19 and the fin unit 17. Thus, the coolingair would not leak at the junction between the fan 19 and the fin unit17.

FIGS. 16 and 17 show a fifth embodiment of this invention.

The fifth embodiment differs from the first embodiment in the structurethat couples the fin unit 17 and the centrifugal fan 19. In any otherstructural respect, the cooling device 15 according to the fifthembodiment is identical to the first embodiment.

As FIGS. 16 and 17 show, a support member 81, which is shaped like aflat plate, couples the fin unit 17 and the centrifugal fan 19. Thesupport member 81 has a first part 82 and a second part 83, which holdthe fin unit 17 and the centrifugal fan 19, respectively. The first part82 and second part 83 lie in the same plane, side by side. The supportmember 81 has first and second screw holes 84 a and 84 b in the firstpart 82, and third and fourth screw holes 84 c and 84 d and a throughhole 85 in the second part 83. The through hole 85 is opposed to theinlet ports 39 of the fan case 37.

The fin unit 17 has a first bracket 87 a and a second bracket 87 b. Thefirst bracket 87 a projects from the first end part 17 a, away from thecentrifugal fan 19. The first bracket 87 a has an insertion hole 88 athat is axially aligned with the first screw hole 84 a. The secondbracket 87 b projects from the second end part 17 b, away from thecentrifugal fan 19. The second bracket 87 b has an insertion hole 88 bthat is axially aligned with the second screw hole 84 b.

The fan case 37 of the centrifugal fan 19 has a pair of insertion holes89 a and 89 b. These insertion holes 89 a and 89 b are axially alignedwith the third and fourth screw holes 84 c and 84 d, respectively.

Two screws 90 fasten the fin unit 17 to the first part 82 of the supportmember 81. The screws 90 are driven into the first and second screwholes 84 a and 84 b, respectively, passing through the insertion holes88 a and 88 b made in the brackets 87 a and 87 b of the fin unit 17.

Two screws 91 fasten the centrifugal fan 19 to the second part 83 of thesupport member 81. The screws 91 are driven into the third and fourthscrew holes 84 c and 84 d, respectively, passing through the insertionholes 89 a and 89 b of the fan case 37.

The fin unit 17 and centrifugal fan 19 are thereby secured to thesupport member 81. In other words, the support member 81 couples the finunit 17 and the centrifugal fan 19, forming an integral unit.

In the fifth embodiment, the fin unit 17 and the centrifugal fan 19 arepositioned with respect to the same thing, i.e., the support member 81.Hence, the fin unit 17 and the centrifugal fan 19 are positionedrelative to each other, with high precision. No gaps are made betweenthe fin unit 17 and the centrifugal fan 19. Thus, the cooling air wouldnot leak at the junction between the fin unit 17 and the centrifugal fan19.

In the present invention, the heat-transferring component is not limitedto the heat pipe. The heat pipe may not be used. If this is the case,liquid coolant may be circulated between the heat receiving portion andthe heat radiating portion. To circulate the liquid coolant so, it isdesired that the heat receiving portion should incorporate a pump thatforces the liquid coolant to the heat radiating portion.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

1. A cooling device for cooling a heat-generating component, comprising:a heat receiving portion thermally connected to the heat-generatingcomponent; a heat radiating portion which radiates heat generated by theheat-generating component, at a position remote from the heat receivingportion; a heat-transferring component which transfers the heatgenerated by the heat-generating component, from the heat receivingportion to the heat radiating portion, and which connects the heatreceiving portion and the heat radiating portion; and a fan whichapplies cooling air to the heat radiating portion, wherein the heatradiating portion includes first and second brackets projecting towardthe fan, and the fan is fixed to the first and second brackets so as tobe held in a position with respect to the heat radiating portion.
 2. Thecooling device according to claim 1, wherein the heat-transferringcomponent is a heat pipe which has a container made of metal, and thecontainer defines a positional relation between the heat receivingportion and the heat radiating portion.
 3. The cooling device accordingto claim 1, wherein the fan includes a fan case and an impeller providedin the fan case, the fan case having an outlet port for dischargingcooling air and being coupled to the heat radiating portion, with theoutlet port opposed to the first and second brackets.
 4. The coolingdevice according to claim 1, wherein the heat receiving portion, theheat radiating portion and the heat-transferring component are assembledtogether, forming one module, and the module is secured to a wiringboard, with the heat receiving portion held on the wiring board.
 5. Thecooling device according to claim 1, wherein the heat radiating portionincludes a plurality of heat-exchanging plates arranged at intervales, afirst end part located at one end of a row of the heat-exchangingplates, and a second end part located at other end of the row of theheat-exchanging plates, the first bracket being formed at the first endpart of the heat radiating portion, the second bracket being formed atthe second end part of the heat radiating portion.
 6. A cooling devicefor cooling a heat-generating component, comprising: a heat receivingportion thermally connected to the heat-generating component; a fin unitwhich is provided remote from the heat receiving portion and has aplurality of heat-exchanging plates arranged at intervals, the fin unithaving a first end part located at one end of a row of theheat-exchanging plates and a second end part located at other end of therow of the heat-exchanging plates; a heat-transferring component whichhas a metal pipe containing coolant and which transfers heat generatedby the heat-generating component, from the heat receiving portion to thefin unit by using the coolant, the metal pipe coupling the heatreceiving portion and the fin unit; and a fan which applies cooling airto the fin unit, wherein the fin unit includes a first bracketprojecting from the first end part toward the fan and a second bracketprojecting from the second end part toward the fan, and the fan is fixedto the first and second brackets so as to be held in a position withrespect to the fin unit.
 7. The cooling device according to claim 6,wherein the fan includes a fan case and an impeller provided in the fancase, the fan case having an outlet port for discharging cooling air andbeing removably held by the first and second brackets, with the outletport opposed to the fin unit.
 8. The cooling device according to claim6, wherein the first bracket is formed at the heat-exchanging platepositioned at the first end part, and the second bracket is formed atthe hear-exchanging plate positioned at the second end part.
 9. Anelectronic apparatus comprising: a housing; a wiring board, which isprovided in the housing; a heat-generating component which is mounted onthe wiring board; and a cooling device which is provided in the housingto cool the heat-generating component and which includes (i) a heatreceiving portion held on the wiring board and thermally connected tothe hear-generating component, (ii) a heat radiating portion forradiating heat generated by the heat-generating component, at a positionremote from the heat receiving portion, (iii) a heat-transferringcomponent for transferring the heat generated by the heat-generatingcomponent, from the heat receiving portion to the heat radiatingportion, and which connects the heat receiving portion and the heatradiating portion, and (iv) a fan for applying cooling air to the heatradiating portion, wherein the heat radiating portion includes first andsecond brackets projecting toward the fan, and the fan is fixed to thefirst and second brackets in the housing so as to be held in a positionwith respect to the heat radiation portion.
 10. The electronic apparatusaccording to claim 9, wherein the heat receiving portion, the heatradiating portion and the heat-transferring component are assembledtogether, forming one module, and the module is secured to the wiringboard, with the heat receiving portion held on the wiring board.
 11. Theelectronic apparatus according to claim 9, wherein the fan comprises afan case and an impeller provided in the fan case, the fan case havingan outlet port for discharging cooling air and being held by the firstand second brackets, with the outlet port opposed to the heat radiatingportion, and the housing has an exhaust port which faces the heatradiating portion.
 12. The electronic apparatus according to claim 9,wherein the heat radiating portion includes a plurality ofheat-exchanging plates arranged at intervals, a first end part locatedat one end of a row of the heat-exchanging plates, and a second end partlocated at other end of row of the heat-exchanging plates, the firstbracket being formed at the first end part of the heat radiatingportion, the second bracket being formed at the second end part of theheat radiating portion.